The laser system used in excimer laser annealing equipment is a gas laser system. In the process of generating laser, a lot of impurities or chemical products will be deposited on the surface of the window. These impurities worsen the spot quality and energy of the laser beam emitted by the excimer laser annealing equipment, causing pulse pollution or poor performance.
At present, the window of the excimer laser generator is a disposable design, and the window can only be replaced at the end of the working life of the laser gas in the laser resonator (e.g., 100 million pulses). This often leads to the following problem: after the gas has been used for a certain period (e.g., 50 million pulses), the surface of the window may be already dirty and the quality and energy of the laser spot are deteriorated. Then the window needs to be replaced. However, in the existing design, the laser gas should be exhausted from the laser resonator before replacing the window, involving heating and cooling processes of the gas laser resonator, the low temperature condenser and the like. This takes a lot of time (about 4 hours) and the laser gas is very expensive. Considering the issues such as the cost and utilization rate, the window is only replaced at the end of the working life of the laser gas (e.g., 100 million pulses), the laser spot and energy at that time have become very poor.